A vapor barrier over a dirt crawlspace floor should be made of what material and have how much overlap when sealed?

A vapor barrier over a dirt crawlspace floor plays a crucial role in preventing moisture from entering the space, which can lead to structural issues and mold growth. The recommended material for an effective vapor barrier is 6-mil polyethylene, which provides a sufficient thickness to resist punctures and tears while effectively blocking moisture migration.

In terms of overlap when sealing the seams of the vapor barrier, 6 inches is optimal. This overlap ensures that if moisture does try to penetrate, it will have a more challenging route due to the overlapping sections, thereby improving the overall effectiveness of the installation. Proper sealing and overlapping are essential to maintain the integrity of the vapor barrier, ensuring a dry crawlspace environment.

Using a different thickness or overlap may not provide the same level of protection or may not conform to the standards typically recommended for vapor barriers in crawlspaces. Thus, a 6-mil polyethylene membrane with a 6-inch overlap strikes the right balance for moisture control in this application.